On Page SEO Questions ?

I was told, and it didn’t seem possible, that search engines can tell if the content from one web site, has been copied into another. Like product descriptions from a manufactures site used in a suppliers site for content, and that would hurt the ranking of the suppliers site…even as I type it it sounds out of the realm of possibility.
Thanks,

I am interested in how you optimize a page for a term that people use for search when the term is not appropriate to use as a main heading for a page or as the text in links pointing to the page.

For example a website I optimize sells hiking tours in a particular region and people will search using terms such as (with the name of the region included):
*hiking tour
*hiking vacation (American market uses the term vacation)
*hiking holiday (British market uses the term holiday)
*Guided hiking tour
*Trekking tour
*Trekking vacation
*Guided walking tour
etc…

Now the company involved already has brochures selling their tours with agents all around the world so they do not want to change the name they give to the tours. Besides the tour names they have are nice sounding and quite appropriate (although would never get searched on unless a person had already heard of it) so I do not think changing the name of a tour to "The (Region name) hiking vacation", etc would be appropriate. Also having category pages called "Hiking Vacations" and then another category page called "Guided Hiking Tours" would start getting confusing to visitors when each category name essentially means the same thing.

Anyway if you could give me legimate techniques to work such search terms into the main headings for these types of pages and into the text of links pointing to them then that would be great.